Field of the Invention
This application concerns an improved electronic fuel injector for an internal combustion engine with structure to precisely control the closing characteristic of the injector's valve which opens and closes to regulate fuel flow to the engine. This precise control produces an extremely accurate fuel delivery for each opening and closing cycle. In contrast, other fuel injectors exhibit relatively imprecise valve control which is usually characterized by a severe impact on valve closing followed by one or more valve rebounds with respect to the valve seat surface. Valve rebounding produces secondary valve openings and causes unplanned and increased fuel delivery to the engine. This excess fuel flow decreases combustion efficiency. Also, it has been found that the fuel delivered during valve rebound is usually poorly atomized, further resulting in combustion inefficiencies.
The subject fuel injector hydraulically cushions the valve closing impact. The hydraulic cushioning is produced by a pair of relatively movable surfaces of the injector which compresses liquid fuel caught therebetween. The resultant force acts on the valve to cushion closing impact of the valve against the seating surface.